Idris Hassan, admitted attacking Lance Scott Walker, also 18, at the hostel where they were both staying in Gledwood Gardens, Hayes on August 15, 2016.

Hassan produced a large knife and stabbed the budding architecture student without warning, just three days before he was due for a mental health assessment.

Lance Scott Walker, 18, who was stabbed to death in Hayes (Image: Metropolitan Police)

The victim jumped out of a window to escape the attack, but Hassan followed him outside and continued to attack him in the street, stabbing him a total of six times.

Hassan denied murder but entered a guilty plea to manslaughter by diminished responsibility at the Old Bailey on Monday April 24.

Prosecutor Ed Brown QC said the plea was accepted by the Crown in light of three psychiatric reports.

Mr Brown said: "Hassan and Mr Walker were both residents of the hostel which provided young people with temporary accommodation.

"The defendant had been placed there following an allegation of criminal damage a few weeks before the killing."

Idris Hassan, 18, walked up behind Lance Scott Walker carrying a plastic bag. He pulled a long knife out and slashed and stabbed him. Later, as Mr Walker lay collapsed on the ground, Hassan stabbed him six more times.